Elizabeth Hardwick, who has died aged 91, was for nearly half a century a prominent figure in New York's literary and cultural life. She was probably best known for her essays and her autobiographical novel Sleepless Nights (1979). But she was also famous for the company she kept. With her then husband, the poet Robert Lowell, she was one of the group of left-liberal intellectuals who founded the New York Review of Books in 1963. Her friends included such writers as Mary McCarthy, Elizabeth Bishop and Philip Roth, as well as influential figures in the publishing world such as Philip Rahv and Jason Epstein.

Hardwick came to New York from the hinterlands. She was born into a large family in Kentucky, a southern border state that tends to produce literary sensibilities very different from those that flourish in the deep south. Her father was a left-leaning blue-collar worker who ran a plumbing and heating business. No doubt it contributed to her alienation from the mint julep school of southern writing that she was a city girl, from Lexington.

After graduating from the University of Kentucky and taking an MA in English, Hardwick moved to New York, where she studied briefly at Columbia University and set up as a freelance writer. In these years, the early 1940s, she also wrote her first novel, The Ghostly Lover (1945), which traces the sentimental education of a young woman from her 16th year to her departure from home to head north. This novel, uneven as it is, deserves more attention than it has received. It paints a portrait of a young woman inhibited from striking out on her own because she feels that her parents, especially her mother, need her to play mother to them. It brought her to the attention of Rahv, the editor at Partisan Review who had 10 years earlier helped launch the career of McCarthy. As in the case of McCarthy, Hardwick had initially attracted attention by way of her acerbic reviews in Partisan.

In 1946 Hardwick met Lowell at a party in Greenwich Village. They met again at Yaddo, the writers' colony in upstate New York, and married in 1949. Lowell was generally regarded as the most gifted English language poet of his generation. However, he was also already launched on a lifetime of manic depression. Shortly after meeting Hardwick, he passed through a violently psychotic phase that led to him being given shock treatment in hospital. During their honeymoon, Lowell entered the depressive aftermath of his manic episode and was confined again. Such behaviour would occur nearly every year for the rest of Hardwick's life with him.

There were good times, too. The couple had a daughter, Harriet, their only child, who survives her, when Hardwick was 40. And they travelled a great deal - to the mid-west, where Lowell taught at the University of Iowa and Hardwick attended a murder trial that became the focus of her second novel, The Simple Truth (1955); to Florence and Amsterdam for extended stays; to Boston, the city of Lowell's blue-blood parents; and to Maine, where they often spent the summer. Many of the best essays in Hardwick's four collections are about places. In 1960, they returned to New York and settled in an apartment on West 67th Street where Hardwick lived until her death.

After 1963, when Hardwick founded the New York Review of Books with Epstein and his wife Barbara, who died last year, and a few others, she no longer had to worry about where to place her work. Soon, other writers, especially women, would be celebrating her dry, lean, often cryptic essays. Cynthia Ozick considered Hardwick to be America's most significant literary essayist; writers as different as Joan Didion, Susan Sontag and Roth agreed in praising her unusual prose style; and Isaiah Berlin spoke of her as the most intelligent woman he had known.

All of these figures, apart from the novelist Ozick, were themselves associated with the New York Review of Books, a publication remarkable for chumminess and logrolling as well as for the talent of its mostly Anglo-American contributors. In the case of Hardwick, the encomia may have been a response to her public conduct as well as to her literary achievement. For the price of her marriage to Lowell was a high one. Hardwick met her fate with considerable dignity and a minimum of self-pity.

In 1970 Lowell left her for a new life in London with the British writer Caroline Blackwood. The public humiliation of abandonment was multiplied by a violation of trust. Suffering with his own guilt, Lowell published poems in which he transcribed parts of telephone conversations and letters that revealed Hardwick's anguish and desire to have her husband back. These poems appear in Lowell's collection The Dolphin (1973). Moreover, between 1970 and 1977, even after Lowell had divorced Hardwick, married Blackwood and had a son by his new wife, Lowell compounded the injury he had done by frantic shuffling between England and America, unable to decide which woman he wanted and needed.

Hardwick was severely tested by Lowell's instability in these years. She continued to go out into society, often with gay men, who had been frequent companions before she married. She also taught writing, retiring in 1985. Her last review, for the New York Review of Books, was in 2003: more than 4,500 words on Nathanael West. Her biography of Herman Melville was published in 2000.

But in general she found her chief consolation in her memories and in her own work, producing Sleepless Nights and Seduction and Betrayal, Women and Literature (1974). The large theme of the latter, and perhaps the great theme of Hardwick's writing about women in general, is the pathos of women's lives insofar as they are inevitably "the second sex", not for the social-political reasons Simone de Beauvoir had proposed, but simply on account of the greater willpower, energy and physical strength of men. There were certain parallels between Thomas Carlyle's high-handed treatment of his wife Jane, about which she writes, and Lowell's treatment of Lizzie.

Hardwick dealt with what she saw as an inevitable condition by making personal loyalty her own highest value. Moreover, before Lowell left her, she had accepted the burden of looking after the deeply disturbed poet by putting her own writing on the back burner. And in her writing she praised women, such as her own mother, who accepted their lives without thinking very much about whys and wherefores. These women - waitresses, cleaners, shop assistants - Hardwick honoured for doing the world's work, usually without much in return from their menfolk. Hardwick maintained her dignity, withstanding the temptation of public displays of rage and exposure of the wrongs done to her.

Lowell was not wholly unaware of her suffering, to judge from the soliloquy he gives the terrified wife in his poem from the 1950s, To Speak of Woe that is in Marriage. It may seem to confirm Hardwick's ultimately despairing sense of the way things were that although Lowell returned to her, in 1977, he died in a taxi on the way from the airport to their apartment later that year.

· Elizabeth Bruce Hardwick, writer, born July 27 1916; died December 2 2007

· This obituary has been revised since the death of the writer in 2003